Formation of a dielectric layer incorporating green, blue and red colorants on an upper substrate of a plasma display panel

ABSTRACT

Disclosed are an upper substrate structure for a plasma display panel including a dielectric layer reinforcing color properties and a fabricating method thereof. The upper substrate structure comprises a sustain electrode formed on an upper glass substrate, a bus electrode formed on the sustain electrode, and an upper substrate dielectric layer formed over a lower part of the surface created by two electrodes and the glass substrate. There is also included a colorant having color properties of red, blue, and green colors, and a protection layer formed on the dielectric layer. The dielectric layer may include one or more colorants so that important properties of PDP such as selective brightness of desired color, color temperature, and color purity improvement can be controlled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a reissue application of U.S. Pat. No. 7,224,123 B2,which is a division of application Ser. No. 10/280,538, filed on Oct.25, 2002, now U.S. Pat. No. 6,914,370, issued on Jul. 5, 2005, whichapplication is hereby incorporated by reference in its entirety. Under35 U.S.C. § 119, this application claims priority to Korean ApplicationSerial No. PATENT-2001-0075505, filed on Nov. 30, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma display panel, andparticularly, a upper substrate structure of a plasma display panel(PDP) and fabricating method thereof for improving a contrast, a colortemperature, and a color purity of PDP.

2. Description of the Background Art

Generally, a flat panel display apparatus can be divided into anemissive display device, and a non-emissive display device. As examplesof the emissive display device, there are a field emission display(FED), a vacuum fluorescent display (VFD), an electro luminescence (EL),and the PDP, etc. In addition, as examples of the non-emissive displaydevice, there are a liquid crystal display (LCD), and an electro chromicdisplay (ECD), etc.

One of the most highlighted display devices is the plasma display panel(PDP). The PDP is a display device using a luminescence of visible raywhich is generated by energy difference when a phosphor is excited byultraviolet ray which is generated in plasma luminescence and returnedto a base status, after injecting discharge gas in a discharge cellwhich is separated by a barrier rib.

The PDP can be divided into a DC type PDP and an AC type PDP accordingto waveform of applied driving voltage and a structure of the dischargecell. A difference between the DC type PDP and the AC type PDP is asfollows.

In case of the DC type PDP, an electrode is exposed on a discharge area,and discharge current is flowed during the voltage is applied.Therefore, a resistance for restricting the current should be made onouter side. However, in case of the AC type PDP, an electrode is coveredby a dielectric layer and a natural capacitive is formed to restrict thecurrent, and the electrode is protected from a shock of ions duringdischarging.

Therefore, the AC type PDP which is used widely will be described in thepresent invention.

FIG. 1 is a cross sectional view showing a conventional PDP.

As shown therein, the conventional PDP comprises: a lower layer 2 formedon an upper part of a lower glass substrate 1; an address electrode 3patterned on some upper part of the lower layer 2 as stripe shape; alower substrate dielectrics 4 formed on an upper front surface of thelower layer 2 including the address electrode 3; a barrier rib 5 formedon the lower substrate dielectrics 4 for preventing a cross-talk with anadjacent discharge cell; a black top formed on an upper side of thebarrier rib 5; a phosphor 6 of red, green, and blue colors formed tocover the black top, a side surface of the barrier rib 5, and the uppersurface of the lower substrate dielectrics 4; a protection layer 7disposed apart a predetermined distance from the upper side of the blacktop, and parallel to the lower substrate dielectrics 4; an uppersubstrate dielectrics 8, to which a bus electrode 9 and a sustainelectrode 10 laminated with each other are inserted, formed on an upperpart of the protection layer 7; and an upper glass substrate 11 formedon an upper part of the upper substrate dielectrics 8 and the sustainelectrode 10. At that time, a discharge gas is filled between the uppersubstrate and the lower substrate. In the discharge gas, He, Ne, Ar, ormixed gas thereof is used to form buffer gas, and a small amount of Xeis used as a source of vacuum ultraviolet ray which makes the phosphor 6be luminescent.

Operation of the conventional PDP will be described as follows.

When an electric field is applied to the address electrode 3, the buselectrode 9, and to the sustain electrode 10 to generate voltagedifference between the upper and lower substrate electrodes, thedischarge gas, that is, He—Ne gas or Ne—Xe gas which is formed insidethe discharge cell defined by the barrier rib 5, the upper substrate andthe lower substrate becomes plasma status to generate vacuum ultravioletrays. The generated vacuum ultraviolet ray excites the phosphor 6 togenerate the visible rays of red, green, or blue color. At that time,the generated visible ray is decided by the kind of phosphor 6, andaccordingly, the respective discharge cell becomes a pixel representingthe red, green, and blue color respectively. The visible ray is radiatedouter side through the transparent upper dielectrics 8 and the upperglass substrate 11.

The upper dielectrics 8 is a layer contacting to the sustain electrode10 using an indium tin oxide (ITO), and to the bus electrode 9 of metalelectrode. And the upper dielectrics 8 uses glass of PbO type havinghigh softening point.

Also, the upper dielectrics 8 includes Pb more than 40%, and the upperdielectrics 8 is made by applying paste in which borosilicate glasspowder of 1˜2 μm diameter and an organic binder are mixed in screenprinting method, and baking at the temperature of 550˜580° C.

The upper substrate dielectrics 8 fabricated as above has a dielectricconstant within 10˜15 range, and a transmittance of visible ray is about85% at peak wavelength. That is, the visible ray generated in thephosphor 6 is not radiated to outer side totally, but loss of light isgenerated as the light passes the protection layer 7, the uppersubstrate dielectrics 8, and the upper glass substrate 11. Also, thetransmittance of the upper substrate dielectrics 8 is for the peakwavelength of the visible rays, and the transmittance is lowered for thewavelengths of blue and red, and therefore, the luminescent efficiencyis lowered greatly.

Also, the plasma generates the visible rays generated from the dischargegas itself, and near infrared ray (NIR) adjacent to the visible ray of0.75˜3 μm wavelength, as well as the ultraviolet rays in discharging.For example, the Ne gas which reduces the discharge voltage and makesthe discharge stable is mixed with the Xe gas, that is, the dischargegas, however, the Ne gas generates the visible ray of orange colorhaving 585 nm wavelength and generates the NIR by the discharging. Inaddition, a means for blocking the NIR, etc., and therefore, a colorpurity is lowered, a contrast is lowered, color temperature applying tothe blue color mainly is reduced, and the signal of a remote controlleris distorted by the NIR.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an uppersubstrate structure for a plasma display panel and fabrication methodthereof which is able to block visible ray and near infrared ray (NIR)generated by a discharge of plasma, to control brightness selectively,to control color temperature, to improve color purity, and to provideoptimized transmittance according to colors represented by respectivepixels by including a dielectric layer for improving color properties ofred, blue, and green colors on the upper substrate of the plasma displaypanel.

To achieve the object of the present invention, there is provided anupper substrate for a plasma display panel comprising: a sustainelectrode formed on some lower part of an upper glass substrate; a buselectrode formed on some lower part of the sustain electrode; adielectric layer formed on a lower entire surface of the sustainelectrode, the bus electrode, and the upper glass substrate, andincluding colorant having color properties of red, blue, and greencolors; and a protection layer formed on a lower part of the dielectriclayer.

Also, to achieve the object of the present invention, there is provideda method for fabricating the upper substrate of PDP comprising the stepsof: depositing ITO on an upper glass substrate, patterning to form asustain electrode; forming a bus electrode on some upper part of thesustain electrode; forming a dielectric layer of single or multiplelayers including colorant which improves color properties of red, blue,and green colors on a lower entire surface of the sustain electrode, thebus electrode, and the upper glass substrate; and forming a protectionlayer on a lower part of the dielectric layer.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a cross-sectional view showing a conventional plasma displaypanel;

FIGS. 2A and 2B are cross-sectional views showing an upper substratestructure of a plasma display panel according to the present invention;

FIG. 3 is a flow chart showing a method for fabricating the uppersubstrate of the plasma display panel according to the presentinvention; and

FIG. 4 is a flow chart showing a method for fabricating a dielectriclayer on the upper substrate of the plasma display panel according tothe present invention as multiple layers successive method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

FIGS. 2A and 2B are cross sectional views showing an upper substratestructure of a plasma display panel (PDP) according to the presentinvention.

As shown therein, an upper substrate of a PDP according to the presentinvention comprises: a sustain electrode 22 formed on some lower part ofan upper glass substrate 21; a bus electrode 23 formed on some lowerpart of the sustain electrode 22; an upper dielectric layer 24 formed onlower entire surface of the sustain electrode 22, the bus electrode, andthe upper glass substrate 21, and including a colorant which improvescolor properties of red, green, and blue colors to control lighttransmittance of desired color; and a protection layer 25 formed on alower part of the upper dielectric layer 24. At that time, the upperdielectric layer 24 is forming single dielectric layer by mixing a kindof colorant having red, green, blue properties in glass powder, or bymixing two or more kinds of colorants of same color type having red,green, blue properties as shown in FIG. 2A. Also, the upper dielectriclayer is forming multiple dielectric layers 26 which are colored bydifferent colors from each other by forming dielectric layers includingcolorants Of different color type having red, green, and blue colorproperty alternately, as shown in FIG. 2B. The upper substrate structureof the PDP according to the present invention will be described asfollows.

The upper glass substrate 21, the sustain electrode 22, the buselectrode 23, and the protection layer 25 have same compositions andstructure as the upper substrate of the conventional PDP. However, theupper dielectric layer 24 functions as a color filter by including thecolorant which improves the red, green, and blue color properties. Thatis, the upper dielectric layer 24 is formed by printing paste in whichan organic binder, glass powder, and the colorant are mixed in screenprinting method, and baking it. Therefore, a certain color is shownaccording to the colorant which is included in the upper dielectriclayer 24, and another colors besides the visible ray corresponding tothat color can be blocked. Also, a filtering effect can be gained asdesired degree by changing the content of the colorant. In addition,when the content of the colorant is small, the filtering effect is alsoreduced, and therefore, the transmittances for the red, green, and bluecolors can be controlled respectively.

Herein, the colorant included in the dielectric layer uses transitionmetal elements oxide, and rare earth elements oxide, more particularly,uses one or two kinds among Nd₂O₃, CoO, and Co₃O₄ representing bluecolor, Fe₂O₃, Er₂O₃ representing red color, and NiO, Cr₂O₃, Pr₂O₃representing green color by mixing. Also, the colorant is mixed to beless than 30 weight % of the glass powder, and diameter of the particleis formed to be within 1˜2 μm.

For example, the upper dielectric layer 24 may be formed by mixing45˜70% of PbO, 1˜10% of SiO₂, 5˜30% of B₂O₃, 0.1˜5% of Al₂O₃, and0.1˜25% of colorant. After that, the paste in which the colorant isincluded is printed, and the paste is baked at the temperature of540˜580° C. so that the thickness of the dielectric layer 24 is to be30˜40 μm.

As described above, the upper dielectric layer includes the colorant toblock the NIR generated from the plasma, and the visible ray of orangecolor having 582 nm of wavelength, and therefore, the color purity canbe improved.

FIG. 3 is a flow chart showing a method for fabricating the uppersubstrate in the PDP according to the present invention.

As shown therein, the method for fabricating the upper substrate in thePDP according to the present invention comprises the steps of:depositing ITO on the upper glass substrate 21, and patterning to formthe sustain electrode 22 (ST10); forming the bus electrode on some upperpart of the sustain electrode 22 (ST12); forming the upper dielectriclayer 24 including the colorant which improved the red, green, bluecolor properties on an upper part of the sustain electrode 22 and thebus electrode 23 (ST14); and forming the protection layer 25 on a lowerpart of the upper dielectric layer (ST16).

Herein, the upper dielectric layer 24 is formed to be a single layer bymixing a kind of colorant among red, green, and blue color with theglass powder, or by mixing two or more kinds of colorants in same colortype having red, green, and blue properties.

Also, as another embodiment of the present invention, the upperdielectric layer 24 can be formed in multiple layers successive method.

FIG. 4 is a flow chart showing a method for fabricating the upperdielectric layer of the PDP according to the present invention inmultiple layer successive method.

As shown therein, the method for fabricating the upper substrate in thePDP according to the present invention comprises the steps of:depositing ITO on the upper glass substrate 21, and patterning to formthe sustain electrode 22 (ST20); forming the bus electrode on some upperpart of the sustain electrode 22 (ST22); forming multiple dielectriclayers 26 colored by different colors by forming dielectric layersincluding different colorants improving the red, green, and blue colorproperties alternately on an upper part of the sustain electrode 22 andthe bus electrode 23 (ST24˜ST34); and forming the protection layer 25 ona lower part of the upper dielectric layer 26 (ST36).

For example, the upper dielectric layers 26 of multiple layers can beformed by applying and baking a layer including Fe₂O₃ of red color typeas a first layer (ST24, ST26), applying and baking a layer including NiOof green color type as a second layer (ST28, ST30), and applying andbaking a layer including Nd₂O₃ of blue color type as a final layer(ST32, ST34). However, in case of forming multiple dielectric layers 26as described above, if the density of the colorant is high, the light isnot transmitted. Therefore, a very small amount of colorant is added tocontrol the transmittance. Also, one or two colorants are added in thesingle dielectric layer 24 or multiple dielectric layer 26 to reduce orincrease brightness uniformity of a certain color for the red, green,and blue colors for controlling entire brightness.

For example, in case of using Nd₂O₃ which is the colorant of blue color,ZnSiO₄:Mn which is the phosphor generating green color visible rays isoverlapped with a peak wavelength on 525 nm wavelength, and therefore,the brightness is reduced. In order to prevent the brightness beingreduced, 0.1˜2% of colorant which improves the green color is mixedtogether in case of using the Nd₂O₃.

Also, to control the color temperature is important in the displaydevice. In addition, in order to reinforce the blue color which affectsto the color temperature most, the dielectric layer 24 including theblue color colorant Nd₂O₃, CoO, Co₃O₄ is used. That is, in case that thetransparent dielectrics is used, the light transmittance is high inorder of green, red, and blue color, and therefore, it is not easy tocontrol the color temperature. However, in case that the dielectricsincluding the colorant according to the present invention is used, thelight transmittance of blue color is increased to control the colortemperature easily. Therefore, the light transmittance of blue color isincreased relatively by the dielectric layer 24 including the Nd₂O₃,CoO, Co₃O₄.

According to the present invention, the upper substrate dielectric layer24 including a kind of colorant among the red, green, and blue colorsmay be constructed, the upper substrate dielectric layer 24 includingtwo or more kinds of colorants in same layer may be constructed, or theupper substrate dielectric layer 24 of multiple layers including a kindof colorant respectively may be constructed.

Therefore, the dielectric layer is functioned as a color filter, andthereby, the properties of the PDP, such as brightness, the colortemperature, and the color purity can be controlled.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

1. A method for fabricating an upper substrate for a plasma displaypanel comprising the steps of: depositing indium tin oxide (ITO) on anupper glass substrate, and patterning the same to form a sustainelectrode; forming a bus electrode on some upper part of the sustainelectrode; forming an upper substrate dielectric layer includingcolorant which reinforces color properties of red, blue, and greencolors on a lower entire surface of the sustain electrode, the buselectrode, and the upper glass substrate; and forming a protection layeron a lower part of the dielectric layer; wherein the upper dielectriclayer is formed by mixing 45˜70% of PbO, 1˜10% of SiO₂, 5˜30% of B₂O₃,0.1˜5% of Al₂O₃, and 0.1˜25% of colorant.
 2. The method of claim 1,wherein the upper substrate dielectric layer is formed to be a singlelayer by mixing a kind of colorant having red, green, and blue colorproperty in glass powder, or mixing two or more kinds of colorants ofsame color type having red, green, blue property in the step of formingthe upper substrate dielectric layer.
 3. The method of claim 1, whereinthe upper substrate dielectric layer is formed to be multiple layerswhich are colored by different colors from each other by formingdielectric layers including colorants of different color type havingred, green, and blue color property alternately in the step of formingthe upper substrate dielectric layer.
 4. The method of claim 1, whereinthe colorant uses one or more kinds among Nd₂O₃, CoO, and Co₃O₄representing blue color, Fe₂O₃, Er₂O₃ representi red color, and NiO,Cr₂O₃, Pr₂O₃ representing green color after mixing them, and the uppersubstrate dielectric layer is a single layer including a kind ofcolorant among the red, green, and blue colors, a single layer includingtwo or more kinds of colorants in the same layer, or multiple layersincluding dielectric layers mixing colorants of different color typehaving red, green, and blue properties alternately.
 5. The method ofclaim 1, wherein the colorant uses one or more kinds among Nd₂O₃, CoO,and Co₃O₄ representing blue color, Fe₂O₃, Er₂O₃ representing red color,and NiO, Cr₂O₃, Pr₂O₃ representing green color after mixing them in thestep of forming the upper substrate dielectric layer.
 6. A method forfabricating an upper substrate for a plasma display panel comprising thesteps of: forming a sustain electrode on an upper class substrate;forming a bus electrode on the sustain electrode; and forming an uppersubstrate dielectric layer comprising a red colorant, a blue colorant,and a green colorant on surfaces of the upper glass substrate, thesustain electrode, and the bus electrode, wherein the upper substratedielectric layer is formed by mixing 45 to 70 percent of PbO, 1 to 10percent of SiO ₂ , 5 to 30 percent of B ₂ O ₃ , 0.1 to 5 percent of Al ₂O ₃ , and 0.1 to 25 percent of the red colorant, the blue colorant andthe green colorant.
 7. The method of claim 6, wherein a thickness of theupper dielectric layer ranges between 30 and 40 μm.
 8. The method ofclaim 6, wherein the blue colorant comprises CO₃ O ₄.
 9. The method ofclaim 6, wherein the green colorant comprises NiO.
 10. The method ofclaim 6, wherein the red colorant comprises Fe₂ O ₃.
 11. The method ofclaim 6, wherein the upper substrate dielectric layer is formed in asingle layer.
 12. The method of claim 6, wherein the upper substratedielectric layer is formed in multiple layers.
 13. The method of claim6, wherein the red colorant, the blue colorant or the green colorantcomprises a transition metal element oxide.
 14. The method of claim 6,wherein the red colorant, the blue colorant or the green colorantcomprises a rare earth element oxide.
 15. The method of claim 6, whereinthe blue colorant is selected from the group consisting essentially ofNd₂ O ₃ , CoO, and Co ₃ O ₄.
 16. The method of claim 15, wherein theforming the upper substrate dielectric layer comprises applying 0.1 to 2percent of the green colorant to the upper substrate dielectric layerwhen Nd₂ O ₃ is used as the blue colorant.
 17. The method of claim 6,wherein the red colorant is selected from the group consistingessentially of Fe₂ O ₃ and Er ₂ O ₂.
 18. The method of claim 6, whereinthe green colorant is selected from the group consisting essentially ofNiO, Cr₂ O ₃ , and Pr ₂ O ₃.